Developing an Amorphous Kerogen Molecular Model Based on Gas Adsorption Isotherms

Lee, Hyeonseok; Ostadhassan, Mehdi; liu, kouqi; Bubach, Bailey

doi:10.26434/chemrxiv.7965152.v1

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“…The methods mentioned are destructive in addition to the limited information they can provide, thus other non−destructive methods such as Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, X−ray photoelectron spectroscopy (XPS), X−ray diffraction (XRD), and 1 H & 13 C solid−state nuclear magnetic resonance ( 13 C−NMR) have been utilized to obtain quantitative structural information from the kerogen [5,8−10]. These direct methods can examine the solid kerogen sample without imposing any alterations so that the results would enable studying the structure and assist in building macromolecular models of kerogen though computational technique at the same time [11,12].…”

Section: Introductionmentioning

confidence: 99%

Structure Evolution of Organic Compounds in Shale Plays by Spectroscopy (1H & 13C−NMR, XPS, and FTIR) Analysis

Lee

Oncel²,

Shokouhimehr³

et al. 2019

Preprint

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Amorphous organic matter in geomaterials also known as kerogen undergoes significant alteration in chemical structure during thermal maturation which is characterized using a combination of solid−state 1 H & 13 C−NMR, X−ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) techniques. For this study, four kerogen samples (type−II) from the Bakken Formation were selected based on the differences in their thermal maturity, as well as representing the pre−oil and oil window stages as measured through organic petrology and bulk geochemical screening of the samples using programmed pyrolysis. Later, organic matter was extracted from selected aliquots for chemical spectroscopy. Results documented a systematic structural change in these four samples where the ratio of CH3/CH2 increased when the maturity increases, along with the presence of shorter aliphatic chain length. Furthermore, the aromatic carbon structure becomes more abundant in higher maturities and oil window stages quantified by 13 C−NMR, XPS, and FTIR. Also, the rate of increase in aromaticity demonstrates a considerable rift between pre−oil window and oil window stages, as verified through bulk geochemical screening of the samples with Rock-Eval 6 pyrolysis HI index. Notably, it's found that kerogen maturation causes the relatively bulky oxygen−related carbon compounds to reduce at the early stages of maturation (pre−oil window) followed by concentration of such compounds at higher maturity stages. Next, the ratio of carbonyl/carboxyl functional groups to aromatic carbon shows an increase in oil window stage while reduction of sulfur in higher maturities was detected mainly in the SOx forms.Finally, nitrogen content of the samples is reported in a variety of forms which varied regardless of the thermal maturation. Its concluded that, the structural and chemical changes that occurs in the organic matter involves defunctionalization of heteroatom functional groups, coupled with an increase in cross−linked carbon in the residual remaining kerogen.

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Section: Introductionmentioning

confidence: 99%

Structure Evolution of Organic Compounds in Shale Plays by Spectroscopy (1H & 13C−NMR, XPS, and FTIR) Analysis

Lee

Oncel²,

Shokouhimehr³

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

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Developing an Amorphous Kerogen Molecular Model Based on Gas Adsorption Isotherms

Abstract: <div>(1) Development of molecular models based on Bakken kerogen experiments using molecular dynamics and quantum mechanics software.<br></div><div>(2) CO2 and N2 gas molecules adsorption simulation on the models was a good agreement with experiments.</div>

Cited by 1 publication

References 23 publications

Structure Evolution of Organic Compounds in Shale Plays by Spectroscopy (1H & 13C−NMR, XPS, and FTIR) Analysis

Structure Evolution of Organic Compounds in Shale Plays by Spectroscopy (1H & 13C−NMR, XPS, and FTIR) Analysis

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Developing an Amorphous Kerogen Molecular Model Based on Gas Adsorption Isotherms

Abstract: <div>(1) Development of molecular models based on Bakken kerogen experiments using molecular dynamics and quantum mechanics software.<br></div><div>(2) CO2 and N2 gas molecules adsorption simulation on the models was a good agreement with experiments.</div>

Cited by 1 publication

References 23 publications

Structure Evolution of Organic Compounds in Shale Plays by Spectroscopy (1H &amp; 13C−NMR, XPS, and FTIR) Analysis

Structure Evolution of Organic Compounds in Shale Plays by Spectroscopy (1H &amp; 13C−NMR, XPS, and FTIR) Analysis

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Structure Evolution of Organic Compounds in Shale Plays by Spectroscopy (1H & 13C−NMR, XPS, and FTIR) Analysis

Structure Evolution of Organic Compounds in Shale Plays by Spectroscopy (1H & 13C−NMR, XPS, and FTIR) Analysis